How Do You Account For Uncertainty in Evacuation Decisions?

The Clash asked, “Should I stay or should I go?” and for those in marine and offshore operations, it’s a familiar question when faced with severe weather evacuation decisions.

The fear behind that question is compounded when you recognize that you must account for uncertainty in evacuation decisions.

Protect your people and assets with customized weather forecasting and decision support provided by DTN Severe and Tropical Weather Suite.

The weather can take a downward turn, and you need to know when to evacuate. Before discussing how to account for uncertainty, you need to look at the reasons you might need to evacuate, the methods at your disposal, and why it matters when you evacuate.

 

Reasons for a Weather-Related Evacuation

There are many reasons that a marine or offshore operation may need to consider evacuation. These include severe weather events, i.e., high winds and waves, hurricanes, tropical storms, and cyclones.

 

Hurricanes

Hurricane season is incredibly dangerous for ships and offshore rigs and is amongst the most common threatening weather events, as meteorologists predict 25-35 tropical weather systems each year. Hurricanes can cause direct damage, such as weather damage to your vessel. They can also cause indirect damage by shutting down shipping lanes and creating waves that are too high for ships to travel in safely.

 

Cyclones and Tropical Storms

Tropical cyclones present serious risks. The strongest known as Hurricanes, Typhoons, etc. depending on the region, can cause direct damage and prevent ships from traveling into or out of the area. 

Hurricanes and cyclones can cause both direct and indirect damage to marine and offshore operations, as well as those onshore facilities that support them.

The best way to protect against hurricanes is evacuation with enough lead time for workers to get safely out of harm’s way before conditions deteriorate.

 

Modes of Evacuation

There are many ways that you can evacuate during severe weather. The following sections outline a few of those methods.

 

Ship-to-Ship Transfer

A ship-to-ship transfer is when you relocate passengers and crew from one ship to another, removing them from the vessel in harm’s way.

 

Ship-to-shore Transfer

Another evacuation method is called for when weather conditions degrade so much that it would not be safe for a rescue boat or helicopter to complete a ship-to-ship transfer. In this case, you will need to use the ship-to-shore transfer method, removing passengers and crew from the vessel via rafts or small boats.

 

Helicopter Evacuation

If weather conditions are so severe or approaching too rapidly that evacuation is not possible via boat, a helicopter evacuation might be deemed necessary. If there are relatively few staff members to evacuate, using a helicopter may make financial sense.

 

Determining the Right Time to Evacuate

Deciding when to evacuate is one of the most important questions that you will have to answer in the face of severe weather. Obviously, evacuating too late means weather conditions are already incredibly dangerous, and your staff is at risk.

Besides the danger presented by the weather conditions, trying to evacuate hastily is risky. There have been instances of accidents, injuries, and even deaths during evacuations that may have been otherwise avoided.

However, evacuating too early has its own dangers. Weather conditions can change, and the need to evacuate may not materialize. There is the danger of “crying wolf” or having too many false alarms. These false alarms create an environment where your staff is desensitized to weather alerts and may not respond when they should.

Additionally, there are financial considerations to evacuating unnecessarily. Evacuating too early costs money and diverts important resources to moving people out of harm’s way.

 

Setting Thresholds for Evacuation

What causes uncertainty in evacuation decisions? The weather system itself presents a lot of uncertainty, as it can be difficult to predict weather conditions that are hours or days away.

Deciding whether you need to evacuate should not be based on your best guess but rather on obvious signs that weather systems are dangerous and life-threatening.

Before deciding when to evacuate, you should set benchmarks or thresholds that prompt a decision one way or another.

You need to set specific thresholds for different types of weather conditions. For example, if weather conditions are severe enough to preclude field operations, it’s time to evacuate. Suppose weather conditions have the potential of being dangerous but not prohibiting work in the field. In that case, you can wait until weather forecasts indicate a greater threat before calling for an evacuation.

As well, your operations will determine different thresholds. For example, the size of your vessel will determine what kind of weather conditions to tolerate. Therefore, your evacuation plan will include thresholds that account for your specific operation, your staff, and the weather conditions that you may encounter.

So, for example, consider an offshore rig. It may be designed to withstand a tropical storm, but not a hurricane. Therefore, your warning threshold limit would need to be above the conditions of a tropical storm but low enough to allow for evacuation in the case of a hurricane.

You should map out warning thresholds for your operations, taking into account the kind of weather systems you can expect and what your equipment or vessels can handle.

 

Accounting for Uncertainty

So how do you account for uncertainty in evacuation decisions?

The best model for planning evacuations is one that gives you as much accurate, reliable information as possible. You need to know how all these factors work together to be able to make prudent decisions.

What kind of weather system is developing, and how severe will it be? How much time do I have before meeting those thresholds? What about my infrastructure? What kind of risks will I encounter while evacuating? What kind of emergency plans are already in place?

The good news? You don’t need to answer these questions alone! The Severe and Tropical Weather Suite by DTN gives you the data and support that you need to make these decisions with confidence.

Our proactive tools help you stay ahead of adverse weather conditions and give you enhanced decision guidance that accounts for your site-specific emergency response and action plan.

While the weather becomes increasingly uncertain, you can face that uncertainty head-on. Make more informed evacuation decisions and keep your staff safe with DTN.